The middle Jurassic siliceous sedimentary cover at the top of Vourinos ophiolites (Greece)

(1)

INTRODUCTION AND GEOLOGICAL SETTING In this study, we describe some radiolarian assemblages that have been extracted from the cherts of the sedimentary cover of the Vourinos ophiolite.

The Vourinos Massif is one of the better known ophio-lites of the Mediterranean area. Till the end of the sixties it was considered an autochthonous magmatic body, em-placed, as an enormous lava flow (Brunn, 1956) or “as a crystal mush or a deforming solid mass rather than as a magma” (Moores, 1969), on the continental crust. Its al-lochthonous position on the metamorphic Pelagonian Zone, now almost unanimously accepted, was firstly put forward by Bortolotti et al. (1969), Zimmerman (1969), Dercourt (1970). Its origin as a portion of an ocean floor was pro-posed by Dercourt (1970), Zimmerman (1972), Bernoulli and Laubscher, (1972), etc.

If its original position was to the west or to the east, or if it belongs to a “Pindos Ocean” or to the “Vardar Ocean” are till now matter of debate. These problems are beyond the scope of this article. In any case, we incline to a provenance from the Vardar Ocean, situated to the east (see Bernoulli and Laubscher, 1972), which, according our paleogeograph-ic and geodynampaleogeograph-ic reconstructions, was the only ocean in the Hellenic area (Bortolotti et al. 2003, with bibl.).

The Vourinos Massif consists of a tectonically disrupted but complete ophiolite sequence, which is interpreted as the product of a supra-subduction zone (Beccaluva et al., 1984). It consists of two main bodies (Western and Eastern Vouri-nos) and three minor satellite bodies (Krapa Hills, Zyghosti Creek and Mikrokastro). The main outcrops expose a ser-pentinite carapace, which coats the main mass of harzbur-gites (with minor lherzolites), dunites and gabbros lato sen-su (Moores, 1969; Jackson et al., 1975; Beccaluva et al., 1984). The satellite bodies are made of harzburgites, often serpentinised, cumulates (present only in the Krapa Hills), an extrusive sequence of IAT type (Beccaluva et al., 1984) which includes pillow basalts, basalts andesites, minor dacites and, at the top, scattered thin levels of cherts and cherty limestones. Basalts and cherts are uncomformably

covered by Lower or Upper Cretaceous limestones.

In spite of the very profound knowledge of the ophiolitic body, no data were available so far on the age of this ophio-lite; only a sample from the amphibolite sole gave a radio-metric age (Ar/Ar) of 171±4 Ma (Spray et al., 1984), which, according to the Pálfi et al. (2000) time scale corresponds to the ?late Bajocian. The Jurassic age of the ophiolite was es-tablished only on calpionellids “of Tithonian (?) or Neoco-mian (?) age” in “brecciated limestones” covering the cherts at Langadhakia (Moores, 1969) and on the Latest Jurassic -Early Cretaceous age of the transgressive limestones on top of the massif (Brunn, 1956; Pichon and Lys, 1976).

The radiolarian assemblages here described provide more exact datings for the Vourinos ophiolite.

BIOSTRATIGRAPHY AND SECTION DESCRIPTION The radiolarians assemblages described, come from four sections of cherts (Fig. 1 and 2), cropping out at the top of the basalts in the satellite bodies of Krapa Hills (Section A), Mikrokastro (Section B) and Zygosti Creek (Sections C and D).

Fourteen samples have been collected for radiolarian analyses. The radiolarians have been extracted from the cherts with hydrofluoric acid at different concentrations, utilising the method proposed by Dumitrica (1970), Pessag-no and Newport (1972), Baumgartner et al. (1981) and De Wever (1982).

The radiolarian zonation based on Unitary Association Zones (UAZ.) proposed by Baumgartner et al. (1995) is adopted herein. The complete faunal assemblages from the examined samples are reported in Fig. 3, the ranges in Fig. 4, and the most important taxa are shown in Plates 1 and 2.

Section A - Krapa Hills

In the Krapa Hills area, near Langadhakia, (NE of Greve-na, behind the Aliakmon River) on the eastern side of the road, pillow basalts that lie at the top of the intrusives, are

Ofioliti, 2003, 28 (2), 95-103 95

THE MIDDLE JURASSIC SILICEOUS SEDIMENTARY COVER AT THE TOP

OF THE VOURINOS OPHIOLITE (GREECE)

Marco Chiari*, Valerio Bortolotti**, Marta Marcucci**, Adonis Photiades*** and Gianfranco Principi**

* C.N.R., Istituto di Geoscienze e Georisorse, Sezione di Firenze, Via La Pira 4, 50121, Italy (e-mail: mchiari@ geo.unifi.it).

** Dipartimento di Scienze della Terra, Università di Firenze, and C.N.R., Istituto di Geoscienze e Georisorse, Sezione di Firenze, Via La Pira 4, 50121, Italy (e-mail: bortolot@geo.unifi.it; marcucci@cesit1.unifi.it; principi@geo.unifi.it). *** Institute of Geology and Mineral Exploration, 70 Messoghion Avenue, 11527 Athens, Greece (e-mail: fotiadis@igme.gr).

Keywords: Vourinos ophiolite, radiolarites, Radiolaria, Middle Jurassic, Vourinos Massif, Greece.

ABSTRACT

The age of the Vourinos ophiolitic massif, pertaining to the Jurassic Tethys Ocean, is not yet exactly known. Four sections in the cherts at the top of the basalts yielded well preserved radiolarian assemblages according to which the age of the end of the “ophiolitic activity” (= the end of ocean spreading) was immediately before or within the latest Bajocian interval. A radiometric (Ar/Ar) age of the metamorphic sole at the base of the ophiolite gave 171±4 Ma (late Bajocian), this is, an age slightly older than that of the cherts: this can mean that the metamorphic soles pertain to an intraoceanic hot thrust, doubling the oceanic crust/lithosphere.

(2)

overlain by about 3 m of red radiolarian cherts grading up-wards to ?Tithonian thin-bedded cherty limestones which yielded not determinable ammonites and belemnites. Fur-ther up, the succession continues with redeposited Jurassic limestones and is uncomformably covered by Upper Creta-ceous limestones (Fig. 2A).

In this section four samples were collected:

- GR 19 (uncertain stratigraphic position) yielded a well preserved radiolarian assemblage. The coexistence of Miri-fusus fragilis praeguadalupensis Baumgartner and Bartolini

with Guexella nudata (Kocher), Mirifusus guadalupensis Pessagno, Protunuma (?) ochiensis Matsuoka, Protunuma quadriperforatus O’Dogherty and Gorican, , Ristola altissi-ma altissi-major Baumgartner and De Wever and Stylocapsa (?) hemicostata Matsuoka indicates a latest Bajocian-early Bathonian age (UAZ. 5). The presence of Hexasaturnalis nakasekoi Dumitrica and Dumitrica-Jud could indicate a more restricted time interval: early Bathonian age.

- GR 20 (about 1.30 m above the basalts). Age not deter-minable due to the poorly preserved fauna.

Fig. 1 - Geological map of Vourinos area (Moores 1969; Mavrides et al. 1982; 1991) modified.

1- Pelagonian basement with gneiss and schists; 2- Triassic-Jurassic Pelagonian marbles; 3- Jurassic “sub-ophiolite” mélange rich in schists and amphibolite soles; 4- More or less serpentinised harzburgites including dunites rich in chromite and pyroxenite bodies; 5- Ultramafic (dunite, wherlite, pyroxenite, trocto-lite, gabbronorite) and mafic (pyroxenite, gabbro) cumulates; 6- Dolerite sheeted dyke complex with pillow lavas intruded by boninitic dykes and overlain by radiolarian red chert sequence; 7- Upper Jurassic limestones; 8- Cretaceous limestones; 9- Upper Maastrichtian flysch; 10- Post-flysch tectonic unit including serpentinites, ophiolitic conglomerates, Upper Cretaceous rudistic limestones and flysch; 11- Upper Aquitanian-Burdigalian (Miocene) molassic sediments; 12- Plio-Quaternary deposits; a- thrust; b- normal fault.

(3)

- GR 21 (about 1.60 m above the basalts). Age not deter-minable due to the poorly preserved fauna.

- GR 22 (about 2.10 m above the basalts). The presence of Ristola altissima major Baumgartner and De Wever indi-cates a latest Bajocian - early Bathonian to late Bathonian-early Callovian age (UAZ. 5-7).

Section B - Mikrokastro

In the Siatista area, about two km from Mikrokastro, on the right of the road towards Siatista, the ophiolite outcrop consists of schistose serpentinites, at the base, and pillow lavas covered by a thin level of red and green radiolarian cherts, at the top. The contact between serpentinites and cherts is covered and probably tectonic. A tectonic contact (fault?) separates also the ophiolitic rocks from a Lower Cretaceous cherty limestone succession (Fig. 2B).

In this section two samples were collected for radiolarian analyses:

- GR 33 (about 1.5 metres above the basalts), yielded a well preserved radiolarian assemblage. The coexistence of

Bernoullius cristatus Baumgartner, Protunuma quadriperfo-ratus O’Dogherty and Gorican and Stichocapsa robusta Matsuoka with Unuma latusicostata (Aita) indicates a latest Bajocian-early Bathonian age (UAZ. 5). The presence of Hexasaturnalis suboblongus (Yao) could indicate a more re-stricted time interval: latest Bajocian age.

- GR 34 (about 1.8 metres above the basalts). The coexis-tence of Guexella nudata (Kocher), Protunuma quadriper-foratus O’Dogherty and Gorican, Ristola altissima major Baumgartner and De Wever and Stichocapsa robusta Mat-suoka with Theocapsomma medvednicensis Gorican indi-cates a latest Bajocian-early Bathonian age (UAZ. 5).

Sections C and D - Zyghosti Creek

In the Zyghosti Creek area, about 10 km S-SW of Kozani, some tens of metres of pillow basalts tectonically cover the harzburgite-dunite complex. Scattered thin out-crops of radiolarian cherts are present at the top of the basalts. A thrust surface separates this succession from the Middle and Upper Jurassic carbonate platform deposits that 97

(4)

GR 19 GR 20 GR 21 GR 22 GR 33 GR 34 GR151 GR 153 GR 154 GR 157

Angulobracchia sp.

Archaeodictyomitra (?) amabilis Aita Archaeodictyomitra (?) sp. cf. A. amabilis Aita Archaeodictyomitra sp. cf. A. apiarium (Rüst)

Archaeodictyomitra sp. cf. A. etrusca Chiari, Cortese and Marcucci Archaeodictyomitra sp. cf. A. spelae Chiari, Cortese and Marcucci Archaeodictyomitra sp.

Bernoullius cristatus Baumgartner

Dictyomitrella (?) kamoensis Mizutani and Kido

Dictyomitrella (?) sp. cf. D. (?) kamoensis Mizutani and Kido Emiluvia premyogii Baumgartner

Emiluvia sp. cf. E. premyogii Baumgartner Emiluvia sp.

Eucyrtidiellum sp. cf. E. unumaense dentatum Baumgartner Eucyrtidiellum sp. cf. E. unumaense pustulatum Baumgartner Eucyrtidiellum unumaense s.l. (Yao)

Eucyrtidiellum sp. Guexella nudata (Kocher)

Hexasaturnalis nakasekoi Dumitrica and Dumitrica-Jud Hexasaturnalis suboblongus (Yao)

Homoeoparonaella (?) sp. cf. H. (?) pseudoewingi Baumgartner Homoeoparonaella sp.

Levileugeo ordinarius Yang & Wang Linaresia sp.

Mirifusus fragilis praeguadalupensis Baumgartner and Bartolini Mirifusus guadalupensis Pessagno

Mirifusus sp. cf. M. fragilis praeguadalupensis Baumgartner and Bartolini Napora sp. cf. N. saginata Takemura

Pantanellium sp.

Paronaella sp. cf. P. broennimanni Pessagno Paronaella bandyi Pessagno

Podobursa helvetica (Rüst) Protunuma (?) ochiensis Matsuoka

Protunuma quadriperforatus O'Dogherty and Gorican Protunuma turbo Matsuoka

Protunuma sp. Protunuma (?) sp.

Pseudoeucyrtis sp. cf. P. sp. J Baumgartner et al. Ristola altissima major Baumgartner and De Wever Saitoum levium De Wever

Saitoum sp. cf. S. pagei Pessagno Saitoum sp.

Sethocapsa funatoensis Aita Sethocapsa sp.

Sethocapsa (?) sp. Stichocapsa convexa Yao Stichocapsa robusta Matsuoka Stichocapsa sp.

Striatojaponicapsa conexa (Matsuoka) Striatojaponicapsa plicarum s.l. (Yao) Striatojaponicapsa sp. cf. S. conexa (Matsuoka)

Striatojaponicapsa sp. cf. S. plicarum ssp. A (Baumgartner et al.) Striatojaponicapsa sp.

Stylocapsa (?) hemicostata Matsuoka Stylocapsa oblongula Kocher Stylocapsa sp. cf. S. oblongula Kocher Stylocapsa tecta Matsuoka

Stylocapsa sp.

Tethysetta dhimenaensis s.l. (Baumgartner) Tethysetta dhimenaensis ssp. A (Baumgartner et al.) Tethysetta sp. cf. T. dhimenaensis ssp. A (Baumgartner et al.) Tetraditryma sp.

Theocapsomma medvednicensis Gorican

Samples Taxa

(5)

99

Fig. 3, continued.

GR 19 GR 20 GR 21 GR 22 GR 33 GR 34 GR151 GR 153 GR 154 GR 157

Theocapsomma sp.

Transhsuum maxwelli gr. (Pessagno) Transhsuum sp. cf. T. maxwelli gr. (Pessagno) Transhsuum sp.

Tritrabs sp. cf. T. casmaliaensis (Pessagno) Unuma gorda Hull

Unuma sp. cf. U. gorda Hull Unuma latusicostatus (Aita) Unuma sp.

Williriedellum sp. cf. W. sp. A Matsuoka Williriedellum sp. cf. W. carpathicum Dumitrica Wrangellium brevicostatum gr. (Ozvoldova) Wrangellium sp. cf. W. brevicostatum gr. (Ozvoldova) Zhamoidellum triangulosa (Tan)

KRAPA Sections Samples Taxa MIKRO-KASTRO ZYGHOSTI A ZYGHOSTI B

Fig. 4 - Range chart of the radiolarian taxa. Radiolarian zonation after Baumgartner et al. (1995), time scale after Channel et al. (1995) and Pálfy et al. (2000). Range of Theocapsomma medvednicensis Gorican after Halamic et al. (1999); Protunuma quadriperforatus O’Dogherty and Gorican after O’Dogherty and Gorican (2002); Hexasaturnalis nakasekoi Dumitrica and Dumitrica-Jud after Dumitrica and Dumitrica-Jud (2003), Hexasaturnalis suboblongus (Yao), Du-mitrica (pers. com.).

(6)

Plate 1 - 1) Archaeodictyomitra (?) amabilis Aita, GR 33, x290; 2) Archaeodictyomitra sp. cf. A. apiarium (Rüst), GR 33, x290; 3)

Ar-chaeodictyomitra sp. cf. A. etrusca Chiari, Cortese and Marcucci, GR 34, x290; 4) ArAr-chaeodictyomitra sp. cf. A. spelae Chiari, Cortese

and Marcucci, GR 33, x290; 5) Bernoullius cristatus Baumgartner, GR 33, x240; 6) Dictyomitrella (?) kamoensis Mizutani and Kido, GR 33, x390; 7) Emiluvia premyogii Baumgartner, GR 19, x186; 8) Eucyrtidiellum unumaense s.l. (Yao), GR 33, x345; 9)

Eucyrtidiel-lum sp. cf. E. unumaense pustulatum Baumgartner, GR 33, x345; 10) Guexella nudata (Kocher), GR 34, x400; 11) Hexasaturnalis nakasekoi Dumitrica and Dumitrica-Jud, GR 19, x137; 12) Hexasaturnalis suboblongus (Yao), GR 33, x137; 13) Levileugeo ordinarius

Yang and Wang, GR 19, x115; 14) Mirifusus fragilis praeguadalupensis Baumgartner and Bartolini, GR 19, x70; 15) Mirifusus

guadalupensis Pessagno, GR 19, x140; 16) Paronaella bandyi Pessagno, GR 19, x160; 17) Podobursa helvetica (Rüst), GR 19, x122;

18) Protunuma (?) ochiensis Matsuoka, GR 19, x258; 19) Protunuma quadriperforatus O’Dogherty and Gorican, GR 19, x228; 20)

Protunuma turbo Matsuoka, GR 33, x228; 21) Protunuma (?) sp., GR 33, x258; 22) Pseudoeucyrtis sp. cf. P. sp. J Baumgartner et al.,

(7)

101

Plate 2 - 1) Saitoum levium De Wever, GR 33, x298; 2) Saitoum sp. cf. S. pagei Pessagno, GR 33, x242; 3) Sethocapsa funatoensis Ai-ta, GR 34, x288; 4) Stichocapsa convexa Yao, GR 19, x214; 5) Stichocapsa robusta Matsuoka, GR 33, x238; 6) Striatojaponicapsa

conexa (Matsuoka), GR 33, x244; 7) Striatojaponicapsa plicarum s.l. (Yao), GR 34, x292; 8) Stylocapsa (?) hemicostata Matsuoka,

GR 19, x216; 9) Stylocapsa oblongula Kocher, GR 154, x365; 10) Stylocapsa tecta Matsuoka, GR 154, x276; 11) Tethysetta

dhime-naensis s.l. (Baumgartner), GR 34, x270; 12) Tethysetta dhimedhime-naensis ssp. A (Baumgartner et al.), GR 33, x270; 13) Theocapsomma medvednicensis Gorican, GR 34, x360; 14) Theocapsomma sp., GR 33, x360; 15) Transhsuum maxwelli gr. (Pessagno), GR 19, x180;

16) Transhsuum sp., GR 22, x180; 17) Tritrabs sp. cf. T. casmaliaensis (Pessagno), GR 19, X158; 18) Unuma latusicostatus (Aita), GR 33, x310; 19) Unuma gorda Hull, GR 34, x308; 20) Williriedellum sp. cf. W. carpathicum, Dumitrica, GR 22, x136; 21) Wrangellium

(8)

transgression that sealed the Jurassic platform and the ophi-olites (Carras et al., 2004, in press).

In the main outcrop of the cherts, on the left side of the creek, about 750 m NE of Aghios Nicolas Chapel, two sec-tions (C and D) about 20 m from one another were sampled (Fig. 2C, 2D).

In the section C three samples were collected:

- GR 151 (about 0.13 metres above the basalts). Age not determinable due to the poorly preserved fauna.

- GR 153 (collected about 0.85 cm above the basalts). The presence of Stichocapsa robusta Matsuoka indicates a latest Bajocian-early Bathonian to late Bathonian-early Callovian age (UAZ. 5-7

In the section D five samples were collected:

- GR 154 (about 0.50 cm above the basalts). The pres-ence of Stylocapsa tecta Matsuoka, Unuma gorda Hull and Stylocapsa oblongula Kocher indicates a middle Bathonian age (UAZ. 6).

FINAL REMARKS

The ages given by the radiolarian cherts at the top of the Vourinos basalts are as follows:

1- Krapa Hills: early Bathonian; 2- Mikrokastro: latest Bajocian;

3- Zyghosti: latest Bajocian-early Bathonian to late Bathonian-early Callovian age, section C; middle Bathon-ian, section D.

We can conclude that in the Vourinos ophiolite the basalt extrusion (and the seafloor spreading?) ended immediately before or within the latest Bajocian - early Callovian age in-terval. This age is slightly younger than the age of the meta-morphism of the amphibolite sole at the base of the massif. We argue that here, as in other cases (Mirdita ophiolites of Albania) the amphibolite soles pertain to an intraoceanic “high-temperature shear zone formed at the base of an over-ridden section of oceanic lithosphere” (Bortolotti et al., 1996; Carosi et al., 1996).

Acknowledgements

The research was supported by M.I.U.R.-COFIN 1998-2000 (V. Bortolotti and G. Principi) and by C.N.R. “Istituto di Geoscienze e Georisorse, Sezione di Firenze”.

Radiolarian micrographs were taken by Maurizio Ulivi, with a Philips 515 SEM of the MEMA, Dept. Scienze della Terra, University of Florence.

We would like to thank Prof. P. Dumitrica, for his fruit-ful suggestions.

G., Danelian T., De Wever P., Dumitrica P., Dumitrica-Jud R., Gorican S., Guex J., Hull D.M., Kito N., Marcucci M., Matsuo-ka A., Murchey B., O’Dogherty L., Savary J., VishnevsMatsuo-kaya V., Widz D. and Yao A., 1995. Middle Jurassic to Early Cretaceous Radiolarian biochronology of Tethys based on Unitary Associa-tions. In: P.O. Baumgartner et al. (Eds.), Middle Jurassic to Lower Cretaceous Radiolaria of Tethys: occurrences, systemat-ics, biochronology. Mém. Géol., Lausanne, 23: 1013-1048. Baumgartner P.O., BjØrklund K.R., Caulet J.P., De Wever P.,

Kel-logg D., Labracherie M., Nakaseko K., Nishimura A., Schaff A., Schimdt-Effing R. and Yao A., 1981. Eurorad II, 1980. Sec-ond European meeting of radiolarian paleontologists: current research on Cenozoic and Mesozoic radiolarians. Ecl. Geol. Helv., 74 (3): 1027-1061.

Beccaluva L., Ohnenstetter D., Ohnenstetter M. and Paupy A., 1984. Two magmatic series with island arc affinities within the Vourinos ophiolite. Contrib. Mineral. Petrol., 85: 253-271. Bernoulli D. and Laubscher H., 1972. The palinspastic problem of

the Hellenides. Ecl. Geol. Helv., 65: 107-118.

Bortolotti V., Carras N., Chiari M., Fazzuoli M., Marcucci M., Photiades A. and Principi G., 2003. The Argolis Peninsula in the palaeogeographic and geodynamic frame of the Hellenides. Ofioliti, 28 (2), this volume.

Bortolotti V., Kodra A., Marroni M., Mustafa F., Pandolfi L., Prin-cipi G. and Saccani E., 1996. Geology and petrology of ophi-olitic sequences in the Mirdita region (Northern Albania). Ofi-oliti, 21: 3-20

Bortolotti V., Dal Piaz G.V. and Passerini P., 1969. Ricerche sulle ofioliti delle Catene Alpine. 5 - Nuove osservazioni sul Massic-cio del Vourinos (Grecia). Boll. Soc. Geol. It., 88: 35-45. Brunn J.H., 1956. Contribution à l’étude géologique du Pinde

septentrional et d’une partie de la Macédoine. Ann. Géol. Pays Hellén., 8, 258 pp.

Carosi R., Kodra A., Marroni M. and Mustafa F., 1996. Deforma-tion history of Jurassic Kalur cherts from the Mirdita nappe, Al-bania. Ofioliti, 21: 41-45.

Carras N., Fazzuoli M. and Photiades A., 2004, in press. Transition from carbonate platform to pelagic deposition (Mid Jurassic -Late Cretaceous), Vourinos Massif, Northern Greece. Riv. It. Pal. Strat., 110.

Channell J.E.T., Erba E., Nakanishi M. and Tamaki K., 1995. Late Jurassic-Early Cretaceous time scale and oceanic magnetic anomaly block model. In: W.A. Berggren, D.V. Kent, M.-P. Aubry and J. Hardenbol (Eds.), Geochronology, time scales and global stratigraphic correlation. SEPM, Spec. Publ., 54: 51-63. Chiari M., Bortolotti V., Marcucci M., Photiades A. and Principi G.,

2003. The Middle Jurassic siliceous sedimentary cover at the top of the Vourinos ophiolite (Greece). Geoitalia 2003, IV° Forum It. Sci. Terra, Bellaria, Settembre 2003, Abstr., p. 720-721. Dercourt J., 1970. L’expansion océanique actuelle et fossile: ses

im-plications géotectoniques. Bull. Soc. Géol. France, 12: 261-317. Dercourt J., 1972. The Canadian Cordillera, the Hellenides and the

sea floor spreading theory. Canad. J. Earth Sci., 9:709-743. De Wever P., 1982. Radiolaires du Trias et du Lias de la Téthys

(systématique, stratigraphie). Soc. Géol. Nord, 7: 1-600. Dumitrica P., 1970. Cryptocephalic and cryptothoracic Nassellaria

in some Mesozoic deposits of Romania. Rev. Roum. Géol. Géophys. Géogr., sér. Géol., 14 (1): 45-124.

Dumitrica P. and Dumitrica-Jud R., (2003). Hexasaturnalis nakasekoi n.sp., a Saturnalid radiolarian species usually con-founded with Hexasaturnalis suboblongus (Yao). Interrad X, Lausanne, Switzerland, September, 2003. Abstract, pag. 53-54. Halamic J, Gorican S., Slovonec D. and Jurkovcec I., 1995. A

Middle Jurassic Radiolarite-Clastic Succession from the Medvednica Mt. (NW Croatia). Geol. Croatica, 52 (1): 29-57. Jackson E.D., Green H.W. and Moores E.M., 1975. The Vourinos

ophiolite, Greece. Cyclic units of lineated cumulates overlying harzburgite tectonites. Geol. Soc. Am. Bull., 86: 390-398.

(9)

Mavrides A., Kelepertzis A., Faugères L., Tsaila-Monopolis, S. Mostler L. and Dimou E., 1982. Geological map of Greece, Siatista Sheet 1:50.000. Athens I.G.M.E.

Mavrides A., Kelepertzis A., Tsaila-Monopolis S. and Skourtsis-Koroneou V., 1991. Geological map of Greece, Knidhi Sheet 1:50.000. Athens I.G.M.E.

Moores E.G., 1969. Petrology and structure of the Vourinos Ophi-olitic Complex of Northern Greece. Geol. Soc. Am., Spec. Pa-per, 118, 74 pp.

O’Dogherty L. and Gorican S., 2002. Protunuma quadriperforatus n.sp., a new species of Jurassic Radiolaria. Micropaleontology 48, Suppl. 1: 35-41.

Pálfy J., Smith P.L and Mortensen J.K., 2000. A U-Pb and 40_Ar/39_{Ar time scale for the Jurassic. Canad. J. Earth Sci., 37:} 1-23.

Pessagno E.A. and Newport L.A., 1972. A technique for extract-ing Radiolaria from radiolarian chert. Micropal., 18 (2): 231-234.

Pichon J.F and Lys M. 1976. Sur l’existence d’une série du Juras-sique à Crétacé inférieur surmontant les ophiolites, dans les collines de Krapa (massif du Vourinos, Grèce). C. R. Acad. Sci. Paris, 282: 523-524.

Spray J.G., Bébien J., Rex D.C. and Roddick J.C., 1984. Age con-straints on the igneous and metamorphic evolution of the Hel-lenic-Dinaric ophiolites. In: J.E. Dixon and A.H.F. Robertson (Eds.), The geological evolution of the Eastern Mediterranean. Geol. Soc. London Spec. Pap., 17: 619-627.

Zimmerman L. Jr., 1969. The Vourinos complex - an allochtho-nous alpine ophiolite in northern Greece. Geol. Soc. Am. Abstr. with Progr. for 1969, p. 245.

103

Received, August 20, 2003 Accepted, November 27, 2003

(10)